JP6771371B2 - Imaging lens and imaging device - Google Patents

Description

The present invention relates to an image pickup lens suitable for a digital camera, a video camera, and the like, and an image pickup device provided with the image pickup lens.

Conventionally, in an imaging lens such as a digital camera, a so-called floating focus method is known in which two or more lens groups are moved in different trajectories to focus. For example, in Patent Documents 1 to 4 below, the lens group on the most object side and the lens group on the image side are fixed at the time of focusing, and a lens group moving between them at the time of focusing (hereinafter referred to as a focus lens group). An optical system adopting a floating focus method in which two) are arranged is disclosed.

Japanese Unexamined Patent Publication No. 2014-6487 Japanese Unexamined Patent Publication No. 2014-142601 Japanese Unexamined Patent Publication No. 2001-21798 Japanese Unexamined Patent Publication No. 2014-219601

Digital cameras are desired to have high maximum magnification, small f-number, and high short-range optical performance. In recent years, there has been an increasing demand for high-speed autofocus. In particular, in macro lenses, the amount of movement of the focus lens group tends to inevitably increase, and weight reduction of the focus lens group has become an important issue. Reducing the weight of the focus lens group not only speeds up autofocus, but also reduces the size and weight of the entire lens system, reduces the power load of the focusing mechanism, reduces the size of the motor, and reduces the operating noise of the motor. Connect.

Another important issue is the suppression of aberration fluctuations during focusing. Even when the focus lens group is configured with a small number of lenses for weight reduction, it is necessary to consider aberration fluctuations, particularly fluctuations in spherical aberration and chromatic aberration.

In the lens system described in Patent Document 1, the maximum shooting magnification at the time of close contact is as low as about 0.15 times. If, in the lens system described in Patent Document 1, if the maximum shooting magnification is to be increased further, it is difficult to suppress the fluctuation of aberration at the time of focusing, particularly the fluctuation of chromatic aberration.

In the lens system described in Patent Document 2, it is very difficult to suppress fluctuations in aberrations due to movement of the focus lens group, particularly fluctuations in spherical aberration and coma. It is very difficult to correct chromatic aberration during close-range photography if an attempt is made to increase the magnification higher than the maximum magnification of a normal image pickup lens.

In the lens system of Example 1 of Patent Document 3, the open F number at the time of photographing an infinity object is 4.0, and it cannot be said that the F number is small. Further, when trying to reduce the F number, it is difficult to suppress fluctuations in aberration during focusing, particularly fluctuations in spherical aberration and chromatic aberration. In the lens system of the other embodiment of Patent Document 3, since the first focus lens group having a large outer diameter of the lens is composed of three or four lenses, the weight of the first focus lens group is large and the focus lens. It is hard to say that the weight of the group has been sufficiently reduced.

The lens system described in Patent Document 4 is also a lens system in which the weight of the first focus lens group is large because the first focus lens group having a large outer diameter of the lens is composed of three lenses.

The present invention has been made in view of the above circumstances, and while having a high maximum shooting magnification and a small F number, the weight of the focus lens group can be reduced, aberration fluctuation during focusing is suppressed, and high optical performance is achieved. It is an object of the present invention to provide an image pickup lens that holds the image and an image pickup device provided with the image pickup lens.

The first imaging lens of the present invention is composed of a first lens group having a positive refractive force, a second lens group, and a third lens group in order from the object side, and the second lens group is a second lens. It has a first focus lens group arranged on the most object side of the group and having a negative refractive force, and a second focus lens group arranged on the image side of the second lens group and having a positive refractive force. When focusing from an infinity object to a short-range object, the first focus lens group and the second focus lens group move by changing the mutual spacing in the optical axis direction, and other than the first and second focus lens groups. The lens group is fixed to the image plane, the first lens group has at least two positive lenses and at least one negative lens, and the first focus lens group has one negative refractive force. It is characterized in that the second focus lens group has at least one positive lens and satisfies all of the following conditional equations (1) to (3) and (8) .
45 <νF1n (1)
65 <νF2p (2)
0.4 <fG1 / f <0.85 (3)
0.95 << | fF1 / fF2 | <2.1 (8)
However,
νF1n: Maximum value of the d-line reference Abbe number of the negative lens in the first focus lens group νF2p: Maximum value of the d-line reference Abbe number of the positive lens in the second focus lens group fG1: Focus of the first lens group Distance f: Focal length of the entire system when the object is in focus at infinity
fF1: Focal length of the first focus lens group
fF2: The focal length of the second focus lens group .
The second imaging lens of the present invention is composed of a first lens group having a positive refractive power, a second lens group, and a third lens group in order from the object side, and the second lens group is the second lens. It has a first focus lens group arranged on the most object side of the group and having a negative refractive power, and a second focus lens group arranged on the image side of the second lens group and having a positive refractive power. When focusing from an infinity object to a short-range object, the first focus lens group and the second focus lens group move by changing the mutual spacing in the optical axis direction, and other than the first and second focus lens groups. The lens group is fixed to the image plane, the first lens group has at least two positive lenses and at least one negative lens, and the first focus lens group includes one negative lens. It consists of less than one lens, the second focus lens group has at least one positive lens, and the third lens group has a negative refractive power and moves in the direction perpendicular to the optical axis to correct image blur. It has an anti-vibration lens group that performs the above, and a fixed lens group that has a positive refractive power and does not move during image blur correction. It is characterized in that all of the following conditional equations (1) to (3) are satisfied.
45 <νF1n (1)
65 <νF2p (2)
0.4 <fG1 / f <0.85 (3)
However,
νF1n: Maximum value of Abbe number based on d-line of negative lens in the first focus lens group
νF2p: Maximum value of Abbe number based on the d-line of the positive lens in the second focus lens group
fG1: Focal length of the first lens group
f: Focal length of the entire system when the object is in focus at infinity
And.
Hereinafter, the first and second image pickup lenses of the present invention are collectively referred to as the image pickup lens of the present invention.

In the image pickup lens of the present invention, it is preferable to satisfy at least one of the following conditional expressions (1-1), (1-2), (3-1), (4), (6) to (9). ..
50 <νF1n <100 (1-1)
55 <νF1n <85 (1-2)
0.45 <fG1 / f <0.8 (3-1)
0.6 << | mF2 / mF1 | <2.2 (4)
0.4 << | fF1 / f | <1.2 (6)
0.3 <fF2 / f <0.9 (7)
0.95 << | fF1 / fF2 | <2.1 (8)
1.1 <TL / f <2.3 (9)
However,
νF1n: Maximum value of the d-line reference Abbe number of the negative lens in the first focus lens group fG1: Focus distance of the first lens group f: Focus distance of the entire system when the object is in focus at infinity mF2: Second focus lens Difference in position in the optical axis direction when the group is in focus and when the closest object is in focus mF1: Position in the optical axis direction when the first focus lens group is in focus and when the closest object is in focus Difference fF1: Focus distance of the first focus lens group fF2: Focus distance of the second focus lens group TL: Distance on the optical axis from the lens surface on the most object side to the lens surface on the image side, and the air equivalent distance It is the sum of the back focus of.

In the image pickup lens of the present invention, it is preferable that the second focus lens group has at least one positive lens and at least one negative lens. The second focus lens group may be composed of two positive lenses and one negative lens.

In the image pickup lens of the present invention, it is preferable that the first lens group consists of five or less lenses including at least three positive lenses and at least one negative lens.

In the image pickup lens of the present invention, it is preferable that the first lens group has at least two positive lenses satisfying the following conditional expression (5).
60 <νG1p (5)
However,
νG1p: The Abbe number based on the d-line of the positive lens in the first lens group.

In the image pickup lens of the present invention, it is preferable that the first focus lens group and the second focus lens group always move in opposite directions when focusing from an infinity object to a short-range object.

In the image pickup lens of the present invention, the third lens group has a vibration-proof lens group that has a negative refractive power and moves in the direction perpendicular to the optical axis to correct image blur, and an image having a positive refractive power. It is preferable to have a fixed lens group that does not move during blur correction. In that case, it is preferable that the anti-vibration lens group includes one positive lens and two negative lenses.

Further, in the image pickup lens of the present invention, the first focus lens group may be configured to include one single lens having a negative refractive power.

In the image pickup lens of the present invention, the aperture diaphragm may be configured to be arranged between the first focus lens group and the second focus lens group.

In the image pickup lens of the present invention, the third lens group may be configured to have a negative refractive power.

The image pickup apparatus of the present invention includes the image pickup lens of the present invention.

It should be noted that the terms "consisting of" and "consisting of" in the present specification mean substantially, and other than those listed as constituent elements, lenses and apertures having substantially no power. , An optical element other than a lens such as a cover glass, a lens flange, a lens barrel, an image sensor, and a mechanical part such as a camera shake correction mechanism may be included.

The above-mentioned "group having a positive refractive power" means that the group as a whole has a positive refractive power. The same applies to the above-mentioned "group having a negative refractive power". The sign of the refractive power of the above group and the sign of the refractive power of the lens shall be considered in the paraxial region if the aspherical surface is included. The above-mentioned "-group" is not necessarily limited to a lens composed of a plurality of lenses, but also includes a lens composed of only one lens. Further, the "single lens" means a lens composed of one lens that is not joined.

The number of lenses described above is the number of lenses that are constituent elements. For example, the number of lenses in a bonded lens in which a plurality of single lenses of different materials are bonded is the number of single lenses constituting the bonded lens. It will be represented by. However, a composite aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical lens are integrally formed and function as one aspherical lens as a whole) is a bonded lens. Is not considered and is treated as a single lens. Further, all of the above conditional expressions are based on the d-line (wavelength 587.56 nm (nanometer)).

According to the present invention, in a lens system consisting of a positive first lens group, a second lens group, and a third lens group in order from the object side and adopting a floating focus method, the configuration of the focus lens group and other lens groups By appropriately setting the above configuration and satisfying a predetermined conditional expression, the weight of the focus lens group can be reduced while having a high maximum shooting magnification and a small F number, and fluctuations in aberration during focusing can be suppressed. It is possible to provide an image pickup lens that maintains high optical performance, and an image pickup device provided with this image pickup lens.

It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 1 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 2 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 3 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 4 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 5 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 6 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 7 of this invention. It is sectional drawing which shows the structure and the optical path of the image pickup lens of Example 8 of this invention. It is each aberration diagram of the image pickup lens of Example 1 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 2 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 3 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 4 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 5 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 6 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 7 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is each aberration diagram of the image pickup lens of Example 8 of this invention, and is a spherical aberration diagram, astigmatism diagram, distortion aberration diagram, and Magnification Chromatic Aberration diagram in order from the left. It is a lateral aberration diagram of the image pickup lens of Example 1 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 2 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 3 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 4 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 5 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 6 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 7 of this invention. It is a lateral aberration diagram of the image pickup lens of Example 8 of this invention. It is a perspective view of the front side of the image pickup apparatus which concerns on one Embodiment of this invention. It is a perspective view of the back side of the image pickup apparatus which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 8 are cross-sectional views showing the configuration and optical path of the imaging lens according to the embodiment of the present invention, and correspond to Examples 1 to 8 described later, respectively. The examples shown in FIGS. 1 to 8 are image pickup lenses capable of taking a picture at the same magnification. Since the basic configuration and the method of drawing the examples shown in FIGS. 1 to 8 are the same, the examples shown in FIG. 1 will be mainly described below. In FIG. 1, the left side is the object side and the right side is the image side, and the optical path shows the on-axis luminous flux 2 and the off-axis luminous flux 3 having the maximum angle of view. In FIG. 1, the upper row labeled "infinity" shows the configuration when the object is in focus at infinity, and the lower row labeled "β = -1.0" shows the focus on a short-distance object at the same magnification. The configuration of is shown.

This imaging lens is composed of a first lens group G1, a second lens group G2, and a third lens group G3 having a positive refractive power in this order from the object side to the image side along the optical axis Z. In the example of FIG. 1, the first lens group G1 is composed of lenses L11 to L15 in order from the object side, and the second lens group G2 is composed of lenses L21, aperture aperture St, and lenses L22 to L24 in order from the object side. The third lens group G3 includes lenses L31 to L39 in order from the object side. The aperture diaphragm St shown in FIG. 1 does not necessarily represent the size and / or shape, but indicates the position on the optical axis Z.

When applying this imaging lens to an imaging device, an infrared cut filter, a low-pass filter, various other filters, and / or a cover glass, etc. are inserted between the optical system and the image plane Sim, depending on the configuration of the imaging device. Since it is preferable to arrange them, FIG. 1 shows an example in which the parallel flat plate-shaped optical member PP assuming these is arranged between the lens system and the image plane Sim. However, in the present invention, the position of the optical member PP is not limited to that shown in FIG. 1, and a configuration in which the optical member PP is omitted is also possible.

The second lens group G2 of this imaging lens is arranged on the most object side of the second lens group G2 and is arranged on the most image side of the first focus lens group F1 having a negative refractive power and the second lens group G2. It has a second focus lens group F2 having a positive refractive power. When focusing from an infinity object to a short-distance object, the first focus lens group F1 and the second focus lens group F2 move while changing the mutual spacing in the optical axis direction, respectively, and the first and second focus lens groups F1 The lens groups other than F2 and F2 are configured to be fixed to the image plane Sim. That is, this image pickup lens employs a floating focus that moves the first focus lens group F1 and the second focus lens group F2 in different trajectories at the time of focusing. The first focus lens group F1 is configured to include two or less lenses including one negative lens, and the second focus lens group F2 is configured to have at least one positive lens.

By moving the two lens groups during focusing as described above, it is possible to secure a high maximum shooting magnification and high optical performance in each shooting region. In the power arrangement of this imaging lens, if the first focus lens group F1 has an appropriate refractive power so that the aberration fluctuation at the time of focusing does not become large, the first focus lens group F1 is arranged closer to the object side of the two focus lens groups. In addition, the lens diameter of the first focus lens group F1 is inevitably larger. Therefore, the weight of the first focus lens group F1 is reduced by forming the first focus lens group F1 with two or less lenses. According to the above configuration, in addition to downsizing and weight reduction of the lens system, optics capable of speeding up autofocus, downsizing the motor by reducing the power load of the focusing mechanism, and reducing the operating noise of the motor, etc. It can be a system.

It is preferable that the first focus lens group F1 and the second focus lens group F2 always move in opposite directions when focusing from an infinity object to a short-distance object. By moving in this way, the amount of movement of each focus lens group can be reduced as compared with the case where the two focus groups are moved in the same direction. For example, as shown in the example of FIG. 1, when focusing from an infinity object to a short-range object, the first focus lens group F1 moves to the image side and the second focus lens group F2 moves to the object side. can do. The two long arrows between the upper and lower rows of FIG. 1 roughly indicate the moving directions of the first focus lens group F1 and the second focus lens group F2 at the time of focusing, and are accurate movement loci. Does not indicate.

The first lens group G1 is configured to have at least two positive lenses and at least one negative lens. With this configuration, spherical aberration and axial chromatic aberration can be satisfactorily corrected. Preferably, the first lens group G1 is composed of five or less lenses including at least three positive lenses and at least one negative lens. In this case, axial chromatic aberration and spherical aberration can be satisfactorily corrected, and the number of lenses in the first lens group G1 is 5 or less, which is advantageous in terms of weight.

The first focus lens group F1 is preferably composed of one single lens having a negative refractive power. By configuring the first focus lens group F1 with only one lens, the focus lens group can be made lighter, and in addition to making the lens system smaller and lighter, the autofocus speed is increased and the focusing mechanism It is possible to reduce the size of the motor by reducing the power load and reduce the operating noise of the motor.

The second focus lens group F2 preferably has at least one positive lens and at least one negative lens. In this case, fluctuations in spherical aberration and axial chromatic aberration during focusing can be satisfactorily suppressed. More preferably, the second focus lens group F2 is composed of two positive lenses and one negative lens. In this case, fluctuations in spherical aberration and axial chromatic aberration during focusing can be suppressed even better, and weight reduction can be achieved by forming the second focus lens group F2 in three elements. it can.

The second lens group G2 may be configured to include lenses other than the first and second focus lens groups F1 and F2. In that case, the second lens group G2 substantially refracts only two or less lenses fixed to the image plane Sim at the time of focusing, the first focus lens group F1, and the second focus lens group F2. It is preferable to provide it as a lens or a lens group having power. In this case, it is possible to configure with a small number of lenses, it becomes easy to secure a moving space between the two focus lens groups, and a high maximum shooting magnification can be obtained.

Alternatively, the second lens group G2 may include only the first focus lens group F1 and the second focus lens group F2 as a lens group having a substantial refractive power. In this case, it becomes easier to secure a moving space for the two focus lens groups and a higher maximum shooting magnification can be obtained as compared with the case where a lens fixed to the image plane Sim at the time of focusing is included. Can be done.

The third lens group G3 preferably has a negative refractive power. In this case, it becomes easy to secure the necessary back focus.

This imaging lens is configured to satisfy all of the following conditional expressions (1) to (3).
45 <νF1n (1)
65 <νF2p (2)
0.4 <fG1 / f <0.85 (3)
However,
νF1n: Maximum value of the d-line reference abbe number of the negative lens in the first focus lens group νF2p: Maximum value of the d-line reference abbe number of the positive lens in the second focus lens group fG1: Focus of the first lens group Distance f: The focal length of the entire system when the object is in focus at infinity.

By satisfying the conditional expression (1), it is possible to suppress fluctuations in chromatic aberration due to movement of the first focus lens group F1. Further, it is preferable to satisfy the following conditional expression (1-1). By making sure that the value does not fall below the lower limit of the conditional expression (1-1), the effect of the conditional expression (1) can be enhanced. By not exceeding the upper limit of the conditional equation (1-1), axial chromatic aberration and magnifying chromatic aberration can be corrected in a well-balanced manner, and various aberrations such as spherical aberration can be ensured by securing the required refractive index. It can be corrected satisfactorily. In order to enhance the effect of the conditional expression (1-1), it is more preferable to satisfy the following conditional expression (1-2).
50 <νF1n <100 (1-1)
55 <νF1n <85 (1-2)

Similarly, by satisfying the conditional expression (2), fluctuations in chromatic aberration due to movement of the second focus lens group F2 can be suppressed. Further, it is preferable to satisfy the following conditional expression (2-1). By making sure that the value does not fall below the lower limit of the conditional expression (2-1), the effect of the conditional expression (2) can be enhanced. By not exceeding the upper limit of the conditional expression (2-1), axial chromatic aberration and magnifying chromatic aberration can be corrected in a well-balanced manner, and various aberrations such as spherical aberration can be ensured by securing the required refractive index. It can be corrected satisfactorily. Furthermore, it is more preferable that the following conditional expression (2-2) is satisfied, and the effect on the lower limit of the conditional expression (2-2) is enhanced by preventing the condition from being less than or equal to the lower limit of the conditional expression (2-2). It becomes possible.
67 <νF2p <100 (2-1)
71 <νF2p <100 (2-2)

By making sure that the value does not fall below the lower limit of the conditional equation (3), the refractive power of the first lens group G1 does not become too strong, so that spherical aberration and chromatic aberration generated in the first lens group G1 can be suppressed. By not exceeding the upper limit of the conditional expression (3), the refractive power of the first lens group G1 does not become too weak, so that the total optical length can be kept short. Further, the height of light rays in the two focus lens groups can be suppressed, which can contribute to the weight reduction of the focus lens groups. In order to enhance the effect of the conditional expression (3), it is preferable to satisfy the following conditional expression (3-1).
0.45 <fG1 / f <0.8 (3-1)

Further, it is preferable that this imaging lens satisfies the following conditional expression (4). By making sure that the value does not fall below the lower limit of the conditional expression (4), the amount of movement of the first focus lens group F1 does not become too large, and the refractive power of the first lens group G1 is strengthened in order to reduce the size of the entire lens system. Since it is not necessary to do too much, it is possible to satisfactorily correct the spherical aberration and the axial chromatic aberration of the entire optical system. Alternatively, in order to reduce the amount of movement of the second focus lens group F2, it is not necessary to make the refractive power of the second focus lens group F2 too strong, and the spherical aberration generated in the second focus lens group F2 can be suppressed to a small value. it can. By not exceeding the upper limit of the conditional expression (4), the amount of movement of the second focus lens group F2 does not become too large, and the fluctuation of the chromatic aberration of magnification due to the movement of the second focus lens group F2 can be suppressed to a small value. it can. Alternatively, in order to reduce the amount of movement of the first focus lens group F1, it is not necessary to make the refractive power of the first focus lens group F1 too strong, and it is possible to suppress curvature of field and chromatic aberration during focusing. it can. In order to enhance the effect of the conditional expression (4), it is preferable to satisfy the following conditional expression (4-1), and it is more preferable to satisfy the following conditional expression (4-2).
0.6 << | mF2 / mF1 | <2.2 (4)
0.7 << | mF2 / mF1 | <2.1 (4-1)
0.85 << | mF2 / mF1 | <2.0 (4-2)
However,
mF2: Difference in position in the optical axis direction between in-focus object in the second focus lens group and in-focus object mF1: In-finity object in focus and closest object in focus in the first focus lens group The difference in position in the optical axis direction of.

The first lens group G1 preferably has at least two positive lenses satisfying the following conditional expression (5), and in such a case, axial chromatic aberration can be satisfactorily corrected. Further, it is preferable to satisfy the following conditional expression (5-1). By not falling below the lower limit of the conditional expression (5-1), it is possible to enhance the effect of the conditional expression (5). By not exceeding the upper limit of the conditional expression (5-1), it is possible to secure a necessary refractive index and satisfactorily correct various aberrations such as spherical aberration.
60 <νG1p (5)
62 <νG1p <100 (5-1)
However,
νG1p: The Abbe number based on the d-line of the positive lens in the first lens group.

Further, it is preferable that this imaging lens satisfies the following conditional expression (6). By making sure that the value does not fall below the lower limit of the conditional equation (6), the refractive power of the first focus lens group F1 does not become too strong, and curvature of field and spherical aberration during focusing can be suppressed. it can. By not exceeding the upper limit of the conditional equation (6), the refractive power of the first focus lens group F1 does not become too weak, and the refractive power of the first lens group G1 does not need to be too strong. Aberration and axial chromatic aberration can be satisfactorily corrected. In addition, the focal length of the entire system does not have to be shortened during short-distance shooting, and a long working distance can be secured. In order to enhance the effect of the conditional expression (6), it is preferable to satisfy the following conditional expression (6-1), and it is more preferable to satisfy the following conditional expression (6-2).
0.4 << | fF1 / f | <1.2 (6)
0.5 << | fF1 / f | <1.1 (6-1)
0.55 << | fF1 / f | <0.95 (6-2)
However,
fF1: Focal length of the first focus lens group f: Focal length of the entire system when the object is in focus at infinity.

Further, it is preferable that this imaging lens satisfies the following conditional expression (7). By making sure that the value does not fall below the lower limit of the conditional expression (7), the refractive power of the second focus lens group F2 does not become too strong, and the spherical aberration generated in the second focus lens group F2 can be suppressed to a small value. .. By not exceeding the upper limit of the conditional expression (7), the amount of movement of the second focus lens group F2 can be suppressed to be small, and the fluctuation of the chromatic aberration of magnification due to the movement of the second focus lens group F2 can be suppressed to be small. Can be done. In order to enhance the effect of the conditional expression (7), it is preferable to satisfy the following conditional expression (7-1).
0.3 <fF2 / f <0.9 (7)
0.4 <fF2 / f <0.8 (7-1)
However,
fF2: Focal length of the second focus lens group f: Focal length of the entire system when the object is in focus at infinity.

Further, it is preferable that this imaging lens satisfies the following conditional expression (8). By making sure that the value does not fall below the lower limit of the conditional expression (8), the refractive power of the first focus lens group F1 does not become too strong, and curvature of field and spherical aberration during focusing can be suppressed. it can. By not exceeding the upper limit of the conditional equation (8), the refractive power of the second focus lens group F2 does not become too strong, and the spherical aberration generated in the second focus lens group F2 can be suppressed to a small value. .. In order to enhance the effect of the conditional expression (8), it is preferable to satisfy the following conditional expression (8-1), and it is more preferable to satisfy the following conditional expression (8-2).
0.95 << | fF1 / fF2 | <2.1 (8)
1.0 << | fF1 / fF2 | <2.0 (8-1)
1.1 << | fF1 / fF2 | <1.9 (8-2)
However,
fF1: Focal length of the first focus lens group fF2: Focal length of the second focus lens group.

Further, it is preferable that this imaging lens satisfies the following conditional expression (9). By making sure that the value does not fall below the lower limit of the conditional expression (9), it is possible to obtain a maximum shooting magnification of about 1x while satisfactorily correcting various aberrations. Further, in order to reduce the total length, the refractive power of each lens group, particularly the focus lens group, is not made too strong, so that the permissible amount of error due to eccentricity of each lens group can be increased. By not exceeding the upper limit of the conditional expression (9), it is possible to prevent the lens system from becoming large. In order to enhance the effect of the conditional expression (9), it is preferable to satisfy the following conditional expression (9-1).
1.1 <TL / f <2.3 (9)
1.2 <TL / f <2.1 (9-1)
However,
TL: The sum of the distance on the optical axis from the lens surface on the most object side to the lens surface on the image side and the back focus in terms of air. F: The focal length of the entire system when the object is in focus at infinity. ..

The third lens group G3 is a vibration-proof lens group that has a negative refractive power and corrects image blur by moving in the direction perpendicular to the optical axis Z, and a fixed lens group that has a positive refractive power and does not move during image blur correction. It is preferable to have a lens group.

The anti-vibration lens group is required to have a small amount of movement during image blur correction. Therefore, it is necessary to strengthen the refractive power of the anti-vibration lens group. Therefore, it is effective to arrange a fixed lens group adjacent to the anti-vibration lens group, which has a refractive power opposite to that of the anti-vibration lens group and does not move during image blur correction. By arranging the fixed lens group, it is possible to suppress the aberration fluctuation when the anti-vibration lens group moves. Further, by using the anti-vibration lens group and the fixed lens group as opposite signs, the aberrations generated in the anti-vibration lens group and the fixed lens group cancel each other out, and the overall aberration can be reduced.

The correction effect can be obtained regardless of the position of the anti-vibration lens group in the lens system, but if it is arranged in the first lens group G1, the outer diameter of the anti-vibration lens group becomes too large, which is preferable. Absent. Further, if a vibration-proof lens group is provided in the focus lens group that moves during focusing, the mechanism becomes complicated, the lens barrel diameter becomes large, and the weight of the focus lens group increases, which is not preferable. Further, if an anti-vibration lens group is arranged between the first focus lens group F1 and the second focus lens group F2, when these two focus lens groups are closest to each other, the two focus lens groups and the anti-vibration lens group are arranged. In order to avoid physical interference with the lens, the movement of the two focus lens groups is restricted, which is disadvantageous for ensuring a high maximum shooting magnification and correcting aberrations in a short-range shooting state. From the above, it is preferable to arrange the anti-vibration lens group in the third lens group G3. In the example of FIG. 1, the third lens group G3 has the anti-vibration lens group G3b, and the first fixed lens group G3a and the second fixed lens group G3a do not move to the object side and the image side of the anti-vibration lens group G3b at the time of image blur correction. A fixed lens group G3c is arranged.

The anti-vibration lens group preferably includes one positive lens and two negative lenses. In this case, fluctuations in various aberrations such as coma, curvature of field, and chromatic aberration during vibration isolation can be suppressed.

The aperture diaphragm St can be configured to be arranged between the first focus lens group F1 and the second focus lens group F2. In this case, the balance between the size of the lens arranged on the image side and the size of the lens arranged on the object side and the burden of correcting the aberration of the lens arranged on the image side with the aperture stop St as the boundary. The lens system can be configured while maintaining a good balance between the burden of correcting the aberration of the lens arranged on the object side and the lens.

It should be noted that the aperture diameter of the aperture stop St may be changed when focusing from an infinity object to a short-distance object. In order to reduce the diameter of the lens on the most object side and the two focus lens groups, it is desirable to block light rays in at least one of the two focus lens groups within a range where there is no practical problem when focusing on a short-range object. .. In that case, it is necessary to adjust the aperture diameter of the aperture stop St according to the fact that the height of the marginal ray at the time of focusing the short-range object is lower than that at the position of the aperture stop St at infinity. Further, the aperture diameter of the aperture diaphragm St may be set so that the luminous flux diameter is smaller than the luminous flux diameter determined by shading in the lens on the most object side or the focus lens group. By setting such an aperture diameter, it is possible to reduce the burden of correcting aberrations when focusing on a short-distance object, reduce the number of lenses, and reduce the size of the lens system.

Specifically, each lens group can be configured as follows, for example. The first lens group G1 may be configured to include four positive lenses and one negative lens in order from the object side, or one negative lens and three in order from the object side. It may be configured to consist of a single positive lens. The first focus lens group F1 may be configured to consist of one negative lens having a concave surface facing the image side, or a positive lens and a negative lens having a concave surface facing the image side are joined in order from the object side. It may be configured to consist of a bonded lens. The second focus lens group F2 may be configured to include a single lens having a positive refractive power in order from the object side, and a bonded lens in which a negative lens and a positive lens are joined in order from the object side. The anti-vibration lens group of the third lens group G3 includes a bonded lens in which a negative lens and a positive lens having a concave surface facing the image side are joined in order from the object side, and a negative lens having a concave surface facing the object side. It may be configured to consist of.

It should be noted that the above-mentioned preferable configurations and possible configurations can be any combination, and it is preferable that they are appropriately selectively adopted according to the required specifications. According to the present embodiment, an imaging lens that has a high maximum shooting magnification and a small F-number, is capable of reducing the weight of the focus lens group, suppresses aberration fluctuations during focusing, and maintains high optical performance. It is possible to achieve it. The "high maximum shooting magnification" here means that the maximum shooting magnification is the same magnification, that is, 1x, and the "small F number" means that the open F number is less than 3.0. ..

Next, numerical examples of the image pickup lens of the present invention will be described.
[Example 1]
The lens configuration of the image pickup lens of the first embodiment is shown in FIG. 1, and the method and configuration thereof are as described above. Therefore, a partial duplication will be omitted here. The imaging lens of Example 1 is composed of a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power in order from the object side. The first lens group G1 is composed of five lenses L11 to L15 in order from the object side. The second lens group G2 includes a first focus lens group F1, an aperture diaphragm St, and a second focus lens group F2 in order from the object side. The first focus lens group F1 is composed of only the lens L21, and the second focus lens group F2 is composed of three lenses L22 to L24 in order from the object side. When focusing from an infinity object to a short-range object, the first focus lens group F1 moves to the image side, the second focus lens group F2 moves to the object side, and the other lens groups move to the image plane Sim. It is fixed.

The third lens group G3 includes a first fixed lens group G3a that is fixed at the time of image blur correction, an anti-vibration lens group G3b that moves in the direction perpendicular to the optical axis Z and performs image blur correction, in order from the object side. It is composed of a second fixed lens group G3c that is fixed at the time of image blur correction. The first fixed lens group G3a is composed of two lenses L31 to L32 in order from the object side, and the anti-vibration lens group G3b is composed of three lenses L33 to L35 in order from the object side. G3c is composed of four lenses L36 to L39 in order from the object side.

Table 1 shows the basic lens data of the image pickup lens of Example 1, and Table 2 shows the specifications and the variable surface spacing. In the Si column of Table 1, the surface of the component on the object side is set as the first, and the surface of the component is numbered i-th (i =) so as to gradually increase toward the image side. 1, 2, 3, ...) Area numbers are shown, the radius of curvature of the i-th surface is shown in the Ri column, and the i-th surface and the i + 1-th surface on the optical axis Z are shown in the Di column. Indicates the surface spacing. In the column of Ndj in Table 1, the d-line (wavelength 587.6 nm) of the j-th (j = 1, 2, 3, ...) Component that gradually increases toward the image side with the component on the object side as the first component. (Nanometer)) shows the refractive index, the νdj column shows the Abbe number of the j-th component based on the d-line, and the θgFj column shows the g-line of the j-th component (wavelength 435.8 nm (wavelength 435.8 nm). The partial dispersion ratio between (nanometer)) and F line (wavelength 486.1 nm (nanometer)) is shown. The partial dispersion ratio θgF between the g-line and the F-line of a certain lens is the refractive index of the lens with respect to the g-line, the F-line, and the C-line (wavelength 656.3 nm (nanometer)), respectively. And NC, it is defined by θgF = (Ng-NF) / (NF-NC).

Here, the sign of the radius of curvature is positive for a surface shape with a convex surface facing the object side and negative for a surface shape with a convex surface facing the image side. Table 1 also shows the aperture stop St and the optical member PP. In Table 1, the surface number and the phrase (St) are described in the column of the surface number of the surface corresponding to the aperture stop St. The value in the bottom column of Di is the distance between the image plane and the image plane Sim in the table. In Table 1, for the variable surface spacing that changes during focusing, the symbol DD [] is used, and the surface number on the object side of this spacing is added in [] and entered in the Di column.

Table 2 shows the focal length f and F number FNo. , The maximum total angle of view 2ω, and the value of the variable surface spacing at the time of focusing are shown with reference to the d-line. (°) in the column of 2ω means that the unit is degree. In Table 2, each value in the state of being in focus on an infinity object is shown in the column described as "infinity", except for the focal length f of the entire system in the state of being in focus on a short-range object at the same magnification. Each value of is shown in the column described as "β = -1.0".

In the data in each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length, but other suitable optical systems can be used even if they are proportionally expanded or contracted. Units can also be used. In addition, in each table shown below, numerical values rounded to a predetermined digit are listed.

9 and 17 show each aberration diagram of the image pickup lens of the first embodiment. In FIG. 9, spherical aberration, astigmatism, distortion, and chromatic aberration of magnification are shown in order from the left. In FIG. 9, each aberration in the state of being in focus on an infinity object is shown in the upper part marked with "infinity", and in the lower part marked with "β = -1.0", a short-distance object having the same magnification is shown. Each aberration in the focused state is shown. In the spherical aberration diagram, d line (wavelength 587.6 nm (nanometer)), C line (wavelength 656.3 nm (nanometer)), F line (wavelength 486.1 nm (nanometer)), and g line (wavelength 435). Aberrations at 0.8 nm (nanometers) are shown by solid black lines, long broken lines, short broken lines, and solid gray lines, respectively. In the astigmatism diagram, the aberration related to the d-line in the sagittal direction is shown by a solid line, and the aberration related to the d-line in the tangential direction is shown by a short dashed line. In the distortion diagram, the aberration related to the d line is shown by a solid line. In the chromatic aberration of magnification diagram, the aberrations related to the C line, F line, and g line are shown by long dashed lines, short dashed lines, and solid gray lines, respectively. FNo. Of the spherical aberration diagram. Means F number, and ω in other aberration diagrams means half angle of view.

In FIG. 17, a lateral aberration diagram in the tangential direction is shown in the left column, and a lateral aberration diagram in the sagittal direction is shown in the right column. In FIG. 17, the upper row labeled "without image blur correction" shows the aberration when there is no image blur correction, and the lower row labeled "with image blur correction" shows the case where the optical axis is tilted by 0.3 degrees. The aberration when the image blur correction is performed by moving the anti-vibration lens group G3b by 0.44 mm is shown. In the aberration diagram of "no image blur correction", in order from the top, the aberration at the angle of view of 0 degrees, the aberration at the angle of view of 80% of the maximum angle of view on the + side, and the aberration at 80% of the maximum angle of view on the-side Shows aberration. Similarly, in the aberration diagram of "with image blur correction", the aberration at the angle of view of 0 degrees, the aberration at the angle of view of 80% of the maximum angle of view on the + side, and the image of 80% of the maximum angle of view on the-side are shown in order from the top. Shows the aberration at the angle. In the transverse aberration diagram, the aberrations related to the d-line, C-line, F-line, and g-line are shown by black solid line, long dashed line, short dashed line, and gray solid line, respectively. All transverse aberration diagrams are in focus on an object at infinity.

Unless otherwise specified, the symbols, meanings, and description methods of the data described in the above description of the first embodiment are the same as those of the following examples. Therefore, duplicate description will be omitted below.

[Example 2]
The lens configuration of the image pickup lens of the second embodiment is shown in FIG. Group configuration of the imaging lens of Example 2, the sign of the refractive power of the first lens group G1 and the third lens group G3, the lens group that moves during focusing, the moving direction thereof, and the anti-vibration lens group that corrects image blur. The lens group fixed at the time of image blur correction and the number of lenses constituting each lens group are the same as those in the first embodiment. The basic lens data of the imaging lens of Example 2 is shown in Table 3, the specifications and variable surface spacing are shown in Table 4, and the aberration diagrams are shown in FIGS. 10 and 18. However, in the lower part marked "with image blur correction" in FIG. 18, if there is image blur with the optical axis tilted by 0.3 degrees, the anti-vibration lens group G3b is moved by 0.44 mm to correct the image blur. Shows the aberration at the time of operation.

[Example 3]
The lens configuration of the image pickup lens of Example 3 is shown in FIG. Group configuration of the imaging lens of Example 3, the sign of the refractive power of the first lens group G1 and the third lens group G3, the lens group that moves during focusing, the moving direction thereof, and the anti-vibration lens group that corrects image blur. The lens group fixed at the time of image blur correction and the number of lenses constituting each lens group are the same as those in the first embodiment. The basic lens data of the image pickup lens of Example 3 is shown in Table 5, the specifications and variable surface spacing are shown in Table 6, and the aberration diagrams are shown in FIGS. 11 and 19. However, in the lower part marked "with image blur correction" in FIG. 19, if there is image blur with the optical axis tilted by 0.3 degrees, the anti-vibration lens group G3b is moved by 0.46 mm to correct the image blur. Shows the aberration at the time of operation.

[Example 4]
The lens configuration of the image pickup lens of Example 4 is shown in FIG. The image pickup lens of Example 4 is composed of a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power in order from the object side. The first lens group G1 is composed of five lenses L11 to L15 in order from the object side. The second lens group G2 includes a first focus lens group F1 and a second focus lens group F2 in order from the object side. The first focus lens group F1 is composed of only the lens L21, and the second focus lens group F2 is composed of three lenses L22 to L24 in order from the object side. When focusing from an infinity object to a short-range object, the first focus lens group F1 moves to the image side, the second focus lens group F2 moves to the object side, and the other lens groups move to the image plane Sim. It is fixed.

The third lens group G3 is, in order from the object side, an aperture diaphragm St, a first fixed lens group G3a fixed at the time of image blur correction, and vibration isolation that moves in a direction perpendicular to the optical axis Z to perform image blur correction. It consists of a lens group G3b and a second fixed lens group G3c that is fixed at the time of image blur correction. The first fixed lens group G3a is composed of two lenses L31 to L32 in order from the object side, and the anti-vibration lens group G3b is composed of three lenses L33 to L35 in order from the object side. G3c consists only of the lens L36.

The basic lens data of the image pickup lens of Example 4 is shown in Table 7, the specifications and variable surface spacing are shown in Table 8, and the aberration diagrams are shown in FIGS. 12 and 20. However, in the lower part marked "with image blur correction" in FIG. 20, when there is image blur with the optical axis tilted by 0.3 degrees, the anti-vibration lens group G3b is moved by 0.40 mm to correct the image blur. Indicates the aberration at the time of operation.

[Example 5]
The lens configuration of the image pickup lens of Example 5 is shown in FIG. Group configuration of the imaging lens of Example 5, the sign of the refractive power of the first lens group G1 and the third lens group G3, the lens group that moves during focusing, the moving direction thereof, and the anti-vibration lens group that corrects image blur. The lens group fixed at the time of image blur correction and the number of lenses constituting each lens group are the same as those in the fourth embodiment. The basic lens data of the image pickup lens of Example 5 is shown in Table 9, the specifications and variable surface spacing are shown in Table 10, and the aberration diagrams are shown in FIGS. 13 and 21. However, in the lower part marked "with image blur correction" in FIG. 21, when there is image blur with the optical axis tilted by 0.3 degrees, the vibration-proof lens group G3b is moved by 0.44 mm to correct the image blur. Shows the aberration at the time of operation.

[Example 6]
The lens configuration of the image pickup lens of Example 6 is shown in FIG. The imaging lens of Example 6 is composed of a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power in order from the object side. The first lens group G1 is composed of four lenses L11 to L14 in order from the object side. The second lens group G2 includes a first focus lens group F1, an aperture diaphragm St, and a second focus lens group F2 in order from the object side. The first focus lens group F1 is composed of two lenses L21 to L22, and the second focus lens group F2 is composed of three lenses L23 to L25 in order from the object side. When focusing from an infinity object to a short-range object, the first focus lens group F1 moves to the image side, the second focus lens group F2 moves to the object side, and the other lens groups move to the image plane Sim. It is fixed.

The number of anti-vibration lens groups for image blur correction of the third lens group G3, the lens group fixed at the time of image blur correction, and the number of lenses constituting each lens group in the third lens group G3 is that of Example 1. Similar to the one.

The basic lens data of the image pickup lens of Example 6 is shown in Table 11, the specifications and variable surface spacing are shown in Table 12, and the aberration diagrams are shown in FIGS. 14 and 22. However, in the lower part marked "with image blur correction" in FIG. 22, when there is image blur in which the optical axis is tilted by 0.3 degrees, the anti-vibration lens group G3b is moved by 0.36 mm to correct the image blur. Shows the aberration at the time of operation.

[Example 7]
The lens configuration of the image pickup lens of Example 7 is shown in FIG. The imaging lens of Example 7 is different from that of Example 6 in that the third lens group G3 has a positive refractive power, but other group configurations, the sign of the refractive power of the first lens group G1, and the focus The number of lenses that move at the time, the direction of movement, the anti-vibration lens group that corrects image blur, the lens group that is fixed during image blur correction, and the number of lenses that make up each lens group are the same as those of Example 6. Is.

The basic lens data of the image pickup lens of Example 7 is shown in Table 13, the specifications and variable surface spacing are shown in Table 14, and the aberration diagrams are shown in FIGS. 15 and 23. However, in the lower part marked "with image blur correction" in FIG. 23, if there is image blur with the optical axis tilted by 0.3 degrees, the vibration-proof lens group G3b is moved by 0.40 mm to correct the image blur. Indicates the aberration at the time of operation.

[Example 8]
The lens configuration of the image pickup lens of Example 8 is shown in FIG. The imaging lens of Example 8 is composed of a first lens group G1 having a positive refractive power, a second lens group G2, and a third lens group G3 having a negative refractive power in order from the object side. The first lens group G1 is composed of five lenses L11 to L15 in order from the object side. The second lens group G2 is composed of a first focus lens group F1, an aperture diaphragm St, two lenses of a lens L22 and a lens L23, and a second focus lens group F2 in order from the object side. The first focus lens group F1 is composed of only the lens L21, and the second focus lens group F2 is composed of three lenses L24 to L26 in order from the object side. The lens L22 and the lens L23 are fixed to the image plane Sim at the time of focusing. When focusing from an infinity object to a short-range object, the first focus lens group F1 moves to the image side, the second focus lens group F2 moves to the object side, and the other lens groups move to the image plane Sim. It is fixed.

The number of anti-vibration lens groups for image blur correction of the third lens group G3, the lens group fixed at the time of image blur correction, and the number of lenses constituting each lens group in the third lens group G3 is that of Example 1. Similar to the one.

The basic lens data of the image pickup lens of Example 8 is shown in Table 15, the specifications and variable surface spacing are shown in Table 16, and the aberration diagrams are shown in FIGS. 16 and 24. However, in the lower part marked "with image blur correction" in FIG. 24, if there is image blur with the optical axis tilted by 0.3 degrees, the anti-vibration lens group G3b is moved by 0.44 mm to correct the image blur. Shows the aberration at the time of operation.

Table 17 shows the corresponding values of the conditional expressions (1) to (9) of the imaging lenses of Examples 1 to 8. In Table 17, the code of the corresponding lens is shown in parentheses in the column of the corresponding value in the conditional expression (5). The values shown in Table 17 are based on the d-line.

As can be seen from the above data, the image pickup lenses of Examples 1 to 8 are capable of a high shooting magnification of the same magnification, have a small F number of 2.91 or less, and reduce the weight of the focus lens group. As a result, aberration fluctuations during focusing are suppressed, and each aberration is satisfactorily corrected to realize high optical performance. The imaging lenses of Examples 1 to 8 are suitable as, for example, medium telephoto to telephoto macro lenses.

Next, the image pickup apparatus according to the embodiment of the present invention will be described. 25A and 25B show external views of the camera 30 which is an image pickup apparatus according to an embodiment of the present invention. FIG. 25A shows a perspective view of the camera 30 as viewed from the front side, and FIG. 25B shows a perspective view of the camera 30 as viewed from the back side. The camera 30 is a single-lens digital camera without a reflex finder to which the interchangeable lens 20 is detachably attached. The interchangeable lens 20 is a lens barrel containing the image pickup lens 1 according to the embodiment of the present invention.

The camera 30 includes a camera body 31, and a shutter button 32 and a power button 33 are provided on the upper surface of the camera body 31. Further, on the back surface of the camera body 31, operation units 34 to 35 and a display unit 36 are provided. The display unit 36 is for displaying the captured image and the image within the angle of view before being captured.

A shooting opening for incident light from a shooting target is provided in the central portion of the front surface of the camera body 31, a mount 37 is provided at a position corresponding to the shooting opening, and the interchangeable lens 20 is connected to the camera body 31 via the mount 37. It is designed to be attached to.

In the camera body 31, an image pickup device such as a CCD (Charge Coupled Device) that outputs an image pickup signal corresponding to the subject image formed by the interchangeable lens 20 and an image pickup signal output from the image pickup element are processed to produce an image. A signal processing circuit to be generated, a recording medium for recording the generated image, and the like are provided. The camera 30 can shoot a still image or a moving image by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, the interplanar spacing, the refractive index, and the Abbe number of each lens are not limited to the values shown in the above numerical examples, and other values can be taken.

Further, the image pickup apparatus of the present invention is not limited to the one having the above configuration, and can be applied to, for example, a single-lens reflex camera, a film camera, a video camera, or the like.

1 Imaging lens 2 On-axis light beam 3 Off-axis light beam 20 Interchangeable lens 30 Camera 31 Camera body 32 Shutter button 33 Power button 34, 35 Operation unit 36 Display unit 37 Mount F1 1st focus lens group F2 2nd focus lens group G1 1st Lens group G2 2nd lens group G3 3rd lens group G3a 1st fixed lens group G3b Anti-vibration lens group G3c 2nd fixed lens group 11-L15, L21-L26, L31-L39 Lens PP Optical member Sim image plane St Aperture aperture Z optical axis

Claims (19)

It consists of a first lens group, a second lens group, and a third lens group having a positive refractive power in order from the object side.
The second lens group is arranged on the most object side of the second lens group and has a negative refractive power, and the first focus lens group and the second lens group are arranged on the most image side and have a positive refractive power. With a second focus lens group
When focusing from an infinity object to a short-distance object, the first focus lens group and the second focus lens group move by changing the mutual distance in the optical axis direction, respectively, and the first and second focus lenses Lens groups other than the group are fixed to the image plane and
The first lens group has at least two positive lenses and at least one negative lens.
The first focus lens group comprises one single lens having a negative refractive power .
The second focus lens group has at least one positive lens.
An imaging lens characterized by satisfying all of the following conditional expressions (1) to (3) and (8) .
45 <νF1n (1)
65 <νF2p (2)
0.4 <fG1 / f <0.85 (3)
0.95 << | fF1 / fF2 | <2.1 (8)
However,
νF1n: Maximum value of the d-line reference Abbe number of the negative lens in the first focus lens group νF2p: Maximum value of the d-line reference Abbe number of the positive lens in the second focus lens group fG1: The first lens Focal length f of group: Focal length of the whole system when focusing on an object at infinity
fF1: Focal length of the first focus lens group
fF2: Let it be the focal length of the second focus lens group . It consists of a first lens group, a second lens group, and a third lens group having a positive refractive power in order from the object side.
The second lens group is arranged on the most object side of the second lens group and has a negative refractive power, and the first focus lens group and the second lens group are arranged on the most image side and have a positive refractive power. With a second focus lens group
When focusing from an infinity object to a short-distance object, the first focus lens group and the second focus lens group move by changing the mutual distance in the optical axis direction, respectively, and the first and second focus lenses Lens groups other than the group are fixed to the image plane and
The first lens group has at least two positive lenses and at least one negative lens.
The first focus lens group consists of two or less lenses including one negative lens.
The second focus lens group has at least one positive lens.
The third lens group has a negative refractive power and moves in a direction perpendicular to the optical axis to correct image blur, and a fixed lens group has a positive refractive power and does not move during the image blur correction. Has a lens group and
The anti-vibration lens group consists of one positive lens and two negative lenses.
An imaging lens characterized by satisfying all of the following conditional expressions (1) to (3).
45 <νF1n (1)
65 <νF2p (2)
0.4 <fG1 / f <0.85 (3)
However,
νF1n: Maximum value of the d-line reference Abbe number of the negative lens in the first focus lens group νF2p: Maximum value of the d-line reference Abbe number of the positive lens in the second focus lens group fG1: The first lens Focal length f of the group: The focal length of the entire system when the object is in focus at infinity. The imaging lens according to claim 1 or 2, which satisfies the following conditional expression (4).
0.6 << | mF2 / mF1 | <2.2 (4)
However,
mF2: Difference in position in the optical axis direction between the in-focus object in focus and the closest object in the second focus lens group mF1: The infinity object in focus and the closest object in the first focus lens group It is the difference in position in the optical axis direction at the time of focusing. The imaging lens according to any one of claims 1 to 3, wherein the second focus lens group has at least one positive lens and at least one negative lens. The imaging lens according to any one of claims 1 to 4 , wherein the second focus lens group includes two positive lenses and one negative lens. The imaging lens according to any one of claims 1 to 5 , wherein the first lens group comprises five or less lenses including at least three positive lenses and at least one negative lens. The imaging lens according to any one of claims 1 to 6 , wherein the first lens group has at least two positive lenses satisfying the following conditional expression (5).
60 <νG1p (5)
However,
νG1p: The Abbe number based on the d-line of the positive lens in the first lens group. The imaging lens according to any one of claims 1 to 7 , wherein the first focus lens group and the second focus lens group always move in opposite directions when focusing from an infinity object to a short-distance object. The third lens group has a negative refractive power and moves in the direction perpendicular to the optical axis to correct the image blur, and the anti-vibration lens group has a positive refractive power and does not move during the image blur correction. The imaging lens according to any one of claims 1 to 8 , which has a lens group. The imaging lens according to claim 9 , wherein the anti-vibration lens group includes one positive lens and two negative lenses. The imaging lens according to any one of claims 1 to 10, wherein the aperture diaphragm is arranged between the first focus lens group and the second focus lens group. The imaging lens according to any one of claims 1 to 11, wherein the third lens group has a negative refractive power. The imaging lens according to any one of claims 1 to 12, which satisfies the following conditional expression (6).
0.4 << | fF1 / f | <1.2 (6)
However,
fF1: Let it be the focal length of the first focus lens group. The imaging lens according to any one of claims 1 to 13, which satisfies the following conditional expression (7).
0.3 <fF2 / f <0.9 (7)
However,
fF2: The focal length of the second focus lens group. The imaging lens according to any one of claims 1 to 14 , which satisfies the following conditional expression (9).
1.1 <TL / f <2.3 (9)
However,
TL: The sum of the distance on the optical axis from the lens surface on the most object side to the lens surface on the image side and the back focus in terms of air conversion distance. The imaging lens according to any one of claims 1 to 15 , which satisfies the following conditional expression (1-1).
50 <νF1n <100 (1-1) The imaging lens according to any one of claims 1 to 15 , which satisfies the following conditional expression (1-2).
55 <νF1n <85 (1-2) The imaging lens according to any one of claims 1 to 17 , which satisfies the following conditional expression (3-1).
0.45 <fG1 / f <0.8 (3-1) An imaging device including the imaging lens according to any one of claims 1 to 18 .